During laparoscopic surgery, instruments known as trocars are commonly used to generate and maintain access channels for the various surgical instruments used to perform surgical operations. Commercially available trocars usually comprise a cannula having a valve body situated at one of its ends. Typically, the cannula has a diameter of about 5 mm or about 12 mm with a length generally within a range of 110mm and 120 mm.
Upon commencement of the surgical operation, the surgeon makes incisions or holes, for example, in the abdomen of the patient, using a corresponding number of trocars each equipped with an accessory for penetrating the various layers of abdominal tissue. Subsequently, each such accessory is extracted and the abdomen is insufflated with an inert gas through one of the trocars so as to generate the desired amount of operating space in the abdominal cavity.
Since the pressure generated inside the patient's abdomen tends to push the trocars outwardly, various methods have been devised to anchor trocars during use. The most common approach utilizes a tube with an inner diameter equal to the outer diameter of the trocar cannula. The tube is also provided with an outer threaded surface which enables the surgeon to “screw it” into the access hole. The tube is then secured to the cannula of the trocar using elastic bands or other friction based systems.
During surgery, all of the necessary instruments are inserted through the trocars. In procedures where internal organ parts or tissue must be removed, for example, gall bladder, intestine parts, tumoral masses, etc., it may necessary to make further incisions in the patient's abdomen of sufficient size to allow passage of the part or tissue to be removed. This often warrants creating additional wounds in the abdomen of greater size than those left by the trocars, with the possibility of contamination through the walls of the incision made during extraction of the parts or tissue hindering post operative recovery of the patient. Morover, as laparoscopic surgical procedures often continue after the extraction step has been performed, and given that the additional incision necessary for extraction may compromise the gas seal, special instruments must often be used to restore the seal.